360 BULLETIN 19 7, UNITED STATES NATIONAL MUSEUM 



ably cowbirds are not too common in the regions where it breeds. 

 Predators doubtless destroy some eggs, yonng and adult birds, but 

 this apparently has not been observed. Accidents may account for 

 some mortality. 



Fall. — Mr. Brewster (1880) draws this attractive picture of the fall 

 migration in Maine : 



At the close of the breeding season, when the brakes are turning brown, and 

 occasional maples along the lake shore begin to glow with the burning tints of 

 autumn, the Philadelphia Vireos join those great congregations of mingled 

 Warblers, Sparrows, Woodpeckers, Titmice, etc., which at this season go trooping 

 through the Maine woods. The specimens taken at Upton, in 1874, were in flocks 

 of this kind, and several of them were shot in low bushes, an apparent exception 

 to the rule previously given. But mixed society among birds, as well as men, 

 is a great leveller of individual traits, and it is by no means uncommon on these 

 occasions to find such tree-loving species as the Bay-breasted, Cape May, Black- 

 hurnian, and Blue Yellow-backed Warblers, the Red-bellied Nuthatch, the Golden- 

 crested Kinglet, and many others, consorting with Winter Wrens, Water 

 Thrushes, and Canada Flycatchers in the thickets by wood-paths, or along the 

 banks of ponds or rivers ; and I know of no more interesting sight, especially if 

 it be a bright September morning, before the sun has risen above the trees. The 

 dark foliage of the alders and vilnirnums is frosted with innumerable dewdrops, 

 which fall in sparkling showers where a Warbler hops or a Woodpecker taps on 

 the slender stems. Yellow and gold and scarlet liveries flash among the glossy 

 leaves, as the active little forms appear and disappear, while the constant 

 rustling and low-toned conversational chirping from the depths of the thicket 

 suggest all sorts of pleasing mysteries. It is a pretty picture, this gathering of 

 the birds in the quiet depths of the forest. 



Winter. — The Philadelphia vireo spends the winter in Central 

 America. Dickey and van Eossem (1938) call it a "common winter 

 visitant at the upper limits of the Arid Lower Tropical Zone both 

 along the interior and coastal mountains" in El Salvador. A^Tiere 

 usually seen, "the altitude was 3,500 feet, and, curiously enough, the 

 species was never seen at any other altitude, even though apparently 

 identical conditions prevailed for at least 500 feet lower. In relative 

 numbers, 'pkiladel'phicus was slightly more common than gilvus and 

 invariably outnumbered the latter when especially favorable trees 

 brought the two species together. Sometimes as many as a dozen 

 jyhiladelphicus could be found in a single food tree, but otherwise the 

 species was, like most vireos, solitary." 



DISTRIBTJTION 



Range. — Central Canada to Panama. 



Breeding range. — The Philadelphia vireo breeds north to north- 

 eastern Alberta (Chippewyan) ; central Saskatchewan (Prince Al- 

 bert) ; southern Manitoba (Duck Mountain and Winnipeg, and has 

 been recorded in summer at Churchill) ; central Ontario (Lac Seul, 

 Moose Factory, Lowbush, and Lake Timiskaming) ; southern Quebec 



